During subterranean drilling operations involving the digging of a ditch, the boring rods disappear progressively in the earth as the drilling continues. For this reason, as the drilling progresses it is necessary to combine rod elements with the rods entering the drilling location and, in this way, to constantly lengthen the boring rods. As a rule, a multitude of rod elements is stored in the area of the drilling device.
During driving, the rod anchored in the drilling axis is introduced into the ground, for example, by means of the rotary drive of a mount. For the purpose of extending the rods in stages, one rod element, respectively, is mounted between the rear end of the rods located in the ground and the rotary drive. Subsequently, the rods are introduced into the ground by an additional section before the next rod element is connected with the rear end of the rod protruding out of the ground. The mounting takes place, for example, on the rod shaft of a drilling mount. For this purpose, the rod element must be positioned on the rod shaft.
A similar process takes place--in reverse order--while the boring rods are being pulled out of the ground. In this way, for example, during the widening of a pilot hole, an expander head is moved through the pilot hole by pulling back the boring rods. For this purpose, the rod element of the boring rod, which is protruding more and more from the ground, must be released, removed from the bore axis and, for example, must be deposited in a magazine. In this case, known arrangements make use of the mechanics used for the placement of the rod elements.
In order to facilitate the positioning of the boring rods, various arrangements are known, wherein, as a rule, several rod elements are located in one magazine. In the area of the magazine, a gripper is located with the aid of which a rod element can be removed from the magazine and can be placed at the rear end of the boring rods located in the ground.
The German Auslegeschrift 2,721,342 describes a magazine device and a device for operating boring rod elements, wherein a gripper, grips boring rod elements located in a magazine by means of an arm, lifts them out and places them in the predetermined position.
The known devices have a more or less costly supply and removal mechanism, which moves the rod elements either mechanically or manually by means of the operating personnel into and out of the drilling axis; they are expensive and require much space. This has a negative effect particularly in the case of mobile drilling devices. The latter must be easy to transport, must be maneuverable and as nonbulky as possible.